I just inherited a 2006 BMW 325i sedan from my sister a couple of weeks ago, she told me she had had trouble with the battery dying on her a couple of times before giving the car to me and over the course of the last 2 weeks I have been having more and more difficulty starting the car. I came across this thread and it seems that by in large the folks who have posted that they did not need to register their new battery and everything was fine either got a replacement OEM battery from the BMW dealer, or an OEM spec battery from the auto store, which would make perfect sense seeing as how the computer would still be telling the alternator to charge the battery properly. But any battery that has different spec ratings from the original would seem to need to be re-registered to work properly. I called around to various independent shops in my area and two of them said they have never heard of the adaptation reset, one said that it definitely needed to be done (yet ironically was cheaper than the others--$55), and another said it definitely did NOT need to be done but told me if I really wanted it done they would do it for me free of charge. Makes me really wonder if I should trust my car to a supposed expert BMW authorized repair shop that didn't even know this needed to be done on a different-spec replacement battery.

I did the same thing by calling around and this is what I found, shops that never heard if the registering said don't need it, while those that did said that they would not do it and would recommend BMW do it. So would you rally trust a shop that has no idea of what you are talking about to put a battery in your car so they can make some money off of you? The shops that did say they wouldn't touch it simply didn't want me to come back to them for any trouble as only BMW can reset / register. I paid the dealer to do it, two year warrantee and now all of my electronics work fine as was having issues with rear defogger and blower.